fifth_column:
As I understand it, the police in Ferguson (after the shooting of Michael Brown, which has yet to be adjudicated) at first tried a hands-off, allow them to blow off steam approach. Which sounds pretty racist to me, but in any case, that was the night that several businesses were looted, and one of them burned and totally destroyed. The heavy-handed tactics, as I understand it, came later. Some nights later, the hands-off approach was again assayed, and more violence ensued. Police crowd control tactics don't seem to be the controlling influence here.
This is why I think that any "protest," in evening hours, should be stopped by force, before a crowd can gather. Not as a general principle, of course, but as a temporary measure, in a situation where after-dark protests have predictably become riots.
As I said before, this makes sense. Contingent, of course, on my information being correct. Not having been there for any of the festivities, I have no first-hand knowledge.